Spark plug



May 4, 1937. E. B. NowoslELsKl SPARK PLUG Filed Jan. 6, 1936 INVENTOR. foin/ara /VoWoS/e/s/f/ BY TORN EY.

*Patented May 4, 1937 UNITED STATES PATENT CFFICE SPARK PLUG Application January 6, 193s, serial No. 57,810

3Claims.

This invention relates to spark plugs, and more particularly to spark plugs of the type wherein the high tension circuit is not only insulated but also shielded or screened to prevent interference with the reception of signals in adjacent radio equipment.

Objects of the invention are to provide an improved method of shielding and insulating the high tension circuit of a spark plug, as Well as a novel structural combination of parts adapted to cooperate in the attainment of improved' shielding and insulating properties.

For example, I provide, for application to a shielding element of the mica sleeve lined type, an improved method of protecting the mica lining, as well as a novel construction of adjacent parts to eliminate the possibility of fraying at4 the edges of the mica, notwithstanding repeated withdrawals and ree-insertions of the connecting cable.

Another object is to secure the cable against the possibility of accidental Withdrawal.

Further purposes will appear in the specilcation and claims.

In the drawing I have illustrated the invention as applied to structures which I regard as con' ventional but representative of other forms which may be employed, and to which the invention may be applied without departure from the principles of the said invention, as disclosed herein.

Fig. l is a longitudinal sectional view of a device embodying the invention;

Fig. 2 is a similar view of a second embodiment; and

Fig. 3l is a transverse end, or bottom plan view ci the device of Fig. 2.

Referring first to Fig. 1, the apertured shielding element l0 is shown as an upward extension of the cylinder engaging base or shell I l, there being an intermediate polygonal portion i2 which receives the wrench or other tool for insertion of the plug in the cylinder wall. The lower portion of the element l0 is also shown as provided with aA polygonal section `i3 facilitating fits attachment to the shell Il, but it is to be'v understood that the two members l0 and l I may be integral if preferred.

In the space within the element lll, there is a cooling and Ventilating chamber surrounding a long thin metallic sleeve I5 lined with a tube I 6 ofrolled mica constituting the wall of a second annular chamber closed at its upper end by a non-conducting sleeve or tube I'l having a metallic skirt I8 surrounding a pair of washers 28, 29 of brass or other compressible metallic (Cl. 12S-169) material, adapted to exert pressure upon a second insulating body 20 composed of a plurality of compressed mica washers, only part of which are visible in the drawing, and corresponding in structural arrangement to the conventional mica 5 washer assembly as illustrated, for example, at 20 in Fig. 2, and also in Hyland Patent No. 1,950,408, granted March 13, 1934.

Between the mica. stack 20 and the center electrode ill there is the usual rolled mica wrapper 23 which extends upwardly for almost the complete length of the spindle i4, the upper portion thereof being confined with the mica stack 20 whenthe upper hollow end 26 ofthe spindle is turned downwardly or upset upon the compressible metallic elements 29 and Eil.

Within the hollow upper portion of the spindle it there is provided a connecting pin 34 having an enlarged lower part 35 against which the upper end of coil spring 36 engages to urge the chisel o edged upper end of the pin into penetrating engagement with the stranded wire cable core 4|.

As shown, the insulated cable 33 is adapted to pass through a metal thimble or elbow 3l, the latter having a hanged ring 38 soldered to its 5 lower end and pivotable within the detachable coupling member 52 threaded on the end of the shielding element III. Before attaching the thimble 3i the spacer tube l1 of loakelite, or other rigid insulating construction, is inserted to flt about electrode connection 34, with its skirt i8 telescoping with washer 28. The upper end of the tube il is hanged, as at t4, to rest upon asbestes disc 45 and overlie the upper edges of mica lining i6, and thus protect the mica lining against iraying or bending out of position.

After passing the cable through the elbow thimble 3l, a metal bracelet or spacing collar 43 is pressed tightly about the rubber coating of the cable, at a point which is a pre-measured distance from the end of the cable.

Coupling nut 52 and thimble 38, the latter being recessed to form an annular ledge 5I, are then moved forward into the assembled relationship shown, wherein thimble 38 serves as a thrust bearing to prevent withdrawal of the cable so iong as coupling member 52 remains in place as shown. When the member 52 is unscrewed from the shielding element I0 and drawn back (together with thimble 31, 38) along the cable, the latter may then be withdrawn and inspected, but spacer tube l1 will remain in place due to the fact that the spun-over end 6I of element In holds upper metallic washer 4l and flange 44 against displacement.

Preferably spacer tube l1 is grooved circumferentially, as indicated at 62, to facilitate heat dissipation and also to provide space for retention of a binding cement, if it is desired to apply 5 such an auxiliary holding substance.

In Fig. 2 the equivalent spacer tube I1 is shown as being held in place by the flanged base 41 of thimble 38', the latter being a part of metal elbow 31', and in turn held by coupling member 52',

when the latter is screwed in position on shielding element l0. Bracelet 43' corresponds in function to bracelet 43 of Fig. 1, and is secured to the cable 33', and by virtue of its engagement with elbow 3l', it prevents disturbance of the electrical connection between 40' and I I' so long as coupling nut 52' remains in place as shown. A's in Fig. l, the cable fits loosely within the spacer tube, so that withdrawal of the former does not necessarily disturb the latter.

For claims to the subject matter of Fig. 2, and claims generic to those features which are common to Figs. 1 and 2, reference is to be had to my co-pending application No. 134,396, filed April 1, 1937.

What I claim is:

l. An ignition shielding structure including a body assembled in a manner to provide a socket for the insertion of an insulated high-tension cable, a metal conduit surrounding the cable and having a metal fitting at its end for detachable engagement With the body, a spacer tube of insulating material within the socket portion of the body, but mechanically free of the insulated cable so that the latter may be withdrawn Without disturbing the spacer tube, means adjacent said fitting to hold said cable and spacer tube in position, and a mica lining for the outer wall of the body, said mica lining being protected at its outer edge by the overlying flanged end oi.' the spacer tube.

2. An ignition shielding structure including a body assembled in a manner to provide a socket for the insertion of an insulated high-tension cable, a metal conduit surrounding the cable, a spacer tube of insulating material within the socket portion of the body, but mechanically free of the insulated cable so that the latter may be withdrawn Without disturbing the spacer tube, means to hold said cable and spacer tube in position, and a mica lining for the outer wall of the body, said mica lining being protected at its outer edge by the overlying flanged end of the spacer tube.

3. An ignition shielding structure including a body assembled in a manner to provide a socket for the insertion of an insulated high-tension cable, a metal conduit surrounding the cable and having detachable engagement with the body,- a mica lining for said socket, a spacer tube of insulating material within the mica lining, but mechanically free of the insulated cable so that the latter may be withdrawn without disturbing the spacer tube, means to hold said cable and spacer tube in position, and metallic means integrated with said spacer tube to engage and aid in the support of said mica lining.

EDWARD B. NOWOSIEISKI. 

